A Measurement-Based Analysis of Active Learning Classroom Retrofit

Effective classroom acoustics ensure speech intelligibility and minimize noise disturbances, particularly in active learning environments with multiple speakers and dynamic interactions. Despite this importance, Brazil lacks specific regulations for classroom acoustics, resulting in limited experience in designing and evaluating such spaces. To address this gap, this study presents the acoustic retrofit of a classroom intended for active instruction, following the guidelines of the German standard DIN 18041. Various materials and installation methods were implemented, with a primary focus on ceiling modifications. Reverberation time (RT) was measured after each intervention to assess the effectiveness of different acoustic treatments. The results demonstrated that the planned interventions significantly improved acoustic conditions, reducing RT at 500Hz from 4.4s to 0.6s. However, sound distribution is not homogeneous in shoebox-shaped rooms with only a single absorptive surface. Consequently, RT cannot be reliably estimated using the Sabine equation, emphasizing the need for detailed acoustic simulations. These findings highlight the importance of a well-planned design to ensure consistent speech intelligibility across all seating positions in active learning environments. As a next step, a post-occupancy evaluation will be conducted to assess the long-term effectiveness of the interventions and gather user feedback on acoustic comfort.